The Air Quality Index Calculator is a vital tool designed to convert the raw measurements of air pollutants into a standardized index that helps the public understand the quality of the air they breathe. The AQI represents the level of pollution ranging from good to hazardous. Each AQI category corresponds to a different level of health concern, making it a practical tool for daily use.
Formula of Air Quality Index Calculator
To calculate the AQI for any pollutant, a specific formula is utilize. Below is a detailed description of the steps involved in calculating the AQI:
Identify the concentration of pollutants: Start by measuring the concentration of key pollutants in the air. Common pollutants include particulate matter (PM10 and PM2.5), ground-level ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide.
Use the AQI breakpoints table: The AQI is calculate using breakpoints that correlate pollutant concentrations to AQI values. Below is an example of breakpoints for PM2.5:
| PM2.5 Concentration (µg/m³) | AQI Range |
|---|---|
| 0.0 - 12.0 | 0 - 50 |
| 12.1 - 35.4 | 51 - 100 |
| 35.5 - 55.4 | 101 - 150 |
| 55.5 - 150.4 | 151 - 200 |
| 150.5 - 250.4 | 201 - 300 |
| 250.5 - 500.4 | 301 - 500 |
Apply the formula: The AQI for each pollutant is calculate using the following formula:
- Where:
- AQI is the Air Quality Index for the pollutant.
- I_high is the AQI value corresponding to C_high.
- I_low is the AQI value corresponding to C_low.
- C_high is the breakpoint concentration greater than or equal to the pollutant concentration.
- C_low is the breakpoint concentration less than or equal to the pollutant concentration.
- C is the measured concentration of the pollutant.
Convenient AQI Conversion Table
For general reference, below is a table that provides quick AQI conversions for commonly encountered situations:
| Condition | AQI Value | Implications |
|---|---|---|
| Good Air Quality | 0 - 50 | No health implications |
| Moderate Air Quality | 51 - 100 | Acceptable air quality |
| Unhealthy for Sensitive Groups | 101 - 150 | Sensitive groups should reduce outdoor activities |
| Unhealthy | 151 - 200 | Everyone should reduce outdoor activities |
| Very Unhealthy | 201 - 300 | Health warnings of emergency conditions |
| Hazardous | 301 - 500 | Health alert: everyone may experience more serious health effects |
Example of Air Quality Index Calculator
Consider a day where the measured concentration of PM2.5 is 40 µg/m³. Using the AQI calculation formula and the breakpoints table:
- C_low = 12.1, I_low = 51
- C_high = 35.4, I_high = 100
Plugging these values into the formula gives:
AQI = (100 - 51) / (35.4 - 12.1) * (40 - 12.1) + 51 = 84.3
This AQI indicates moderate air quality.
Most Common FAQs
An AQI over 150 is consider unhealthy, and it is recommended that everyone limit prolonged outdoor exertion.
The AQI can be update hourly, depending on local air monitoring stations and data processing.
Yes, calculate the AQI for each pollutant separately and use the highest value as the overall AQI for the location.